Traditional devices for dilating body cavities include medical or surgical instruments known as specula, dilators, or retractors.
A conventional speculum is used to enlarge an existing body cavity, such as during vaginal or rectal examinations. Such dilators are traditionally made of surgical steel which may be sterilized after the examination of each patent.
A drawback of steel devices is that they tend to feel cold when contacting the human tissue which is spread apart during examination or surgery. Typical examinations of body orifices such as described above are anxiety producing. Accordingly, the added shock of a cold surgical instrument against the tissue of the patient heightens the anxiousness of the patient. Furthermore, anxious patients may have more tightly tensed muscles which impede the spreading open of the cavity. The physical examination is thus hampered and slowed.
Furthermore, conventional steel dilators must be sterilized after each use to prevent cross-contamination between patients. Such sterilization is time-consuming, costly, and requires that the physician have multiple instruments available so that a sterilized dilator is at hand while the other dilators are being cleaned between uses.
U.S. Pat. No. 4,807,600 to Hayes discloses a speculum protector which is essentially a disposable cover for blades of a reusable speculum. The speculum disclosed in Hayes is a traditional duck bill speculum having two opposed concavo-convex blades movable outwardly relative to each other and is particularly suited for vaginal examinations.
It is also known to place the cut off finger of a surgical glove or a condom over the blades of a steel dilator. As with the features of the above-described Hayes speculum protector, these plastic coverings for preventing contamination of the instrument are satisfactory. However, given the heightened awareness of the virility and virulence of sexually transmitted diseases and the cost of sterilizing surgical instruments even on an occasional basis, there is a need for a dilator which provides a more consistent, better solution to the problem of disease transmission.
U.S. Pat. No. 3,702,606 to Barnard discloses a duck bill speculum injection molded from a plastic such as PERSPEX.TM..
U.S. Pat. No. 350,721 to Cooper discloses a speculum having three elongated arms, one of which is made integral with a crossbar for moving the other two arms outwardly as it is moved.
U.S. Pat. No. 2,083,573 to Morgan discloses a speculum having four elongated blades, a main object of which is to provide for parallel movement of the blades during both divergence and convergence thereof. Although arcuate paths of the blades are possible when the blades are moved outwardly, Morgan intends that in actual practice the operator manipulates the handles so as to cause blade movement along radii.
German Auslegeschrift 1,273,135 to Melanovsky dated Jul. 18, 1968, discloses a cervical dilator having expander arms movable radially outwardly by means of an adjusting disk with spiral grooves meshing with guide members associated with the expander arms. Although the configuration of the Melanovsky grooves is intended to afford a self-locking action for maintaining the expander arms in the desired position, the dilator is unsuited for one-handed operation.